The present invention relates to an improved apparatus and method for removing molded articles from a multi-cavity injection mold and loading inserts into the cavity of the same mold. The apparatus and the method of the present invention have particular utility in the manufacture of laminated plastic containers suitable for holding foods, beverages and chemicals.
The art of molding through, around or adjacent inserts placed in an injection molding cavity are well known in the injection molding industry. A number of different methods have been developed to load the inserts to be included within the molded article and to unload the molded article from the machine. Typically, the method that is used for a particular molding system takes into account the size, shape and number of the inserts to be loaded and such other factors as cost, degree of automation, complexity, speed and reliability.
For example, U.S. Pat. No. 3,837,772 to Van de Walker et al. illustrates a top entry robot system which is fed with inserts which are held in place on the robot using a vacuum. Upon opening the mold, a transfer plate moves into position opposite core pins in the mold. When the transfer plate is in this position, the vacuum is substituted by a pressure which forces the inserts onto the core pins where they are held in place by a vacuum applied to the core pins. If the inserts are open-ended, this vacuum method may not be feasible or effective.
U.S. Pat. No. 4,648,825 to Heil et al. illustrates a different system having a horizontal gantry structure which spans perpendicularly across the injection machine. An arm which depends from one end of the gantry secures a load carrier while another arm depending from the opposite end of the gantry secures an unload carrier. The arms move toward each other when the mold is opened to perform the loading and unloading functions. This approach disadvantageously requires two tooling arms, occupies substantial floor space on both sides of the machine, and is very costly.
European patent document No. 0 357 777 to Orimoto et al. shows a plastic mouth insert which is loaded into the injection mold. The purpose of this insert is to provide heat resistance in the neck finish area which is required during subsequent operations in making a container. As discussed in this patent document, it is advantageous to accurately center the insert in the cavity and to support it in place as the injected plastic flows around it. For the purpose of loading the insert into the injection mold, it is recommended to position the insert in place between the mold splits, then close the splits in the conventional manner. In some cases, it may not be feasible or practical to deliver the insert from the carrier plate to its final position in the mold due to space restrictions or alignment problems and a co-operative effort from both carrier plate and mold are essential. Where molds already employ the use of moving mold ejection components, the return stroke of the components can provide the double function of insert retrieval, saving redundant motion and time. Hence, the loading device should also be capable of working in concert with the most advanced molds as previously discussed, which incorporate non-rectilinear mold splits motion.